Air-conditioning systems basically consist of a circuit including two heat exchangers, a controlled expansion valve and a pump, the circuit being filled with a refrigerant. The gaseous refrigerant is compressed and condensed by the pump while releasing heat in a heat exchanger in the high-pressure part (HP) of the system. The refrigerant is expanded on the valve and absorbs heat when vaporization takes place in a heat exchanger in the low-pressure part (LP) of the system, thus cooling a medium contained therein. The vaporized refrigerant in the low-pressure part (LP) of the system is recirculated to the pump.
For filling or replenishing an air-conditioning system with a refrigerant, this system is routinely drained by a vacuum pump and, in this way, is also dehumidified. Afterwards, the air-conditioning system is filled, and the pressure in the high-pressure part (HP) and downstream of the expansion valve in the low-pressure part (LP) is set to specific values, depending on the vapor pressure temperature of the refrigerant used. The efficiency of the air-conditioning system depends, among other things, on this set of values (i.e., settings). For optimum configuration of the settings of an air-conditioning system, it is particularly important that a trend can be observed during the configuration, and that an alignment of values before/afterwards is possible so as to shorten the time required for optimally adjusting the system settings.
Installation aids or service devices are known for the maintenance and modification of the settings of air-conditioning systems. These consist of a valve block including valves and manometers (i.e., pressure gauges). Usually, the color of the ports, valves and manometers for the high-pressure part (HP) of the air-conditioning system is red, and the color of the ports, valves and manometers for its low-pressure part (LP) is blue.
Such installation aids also have a so-called service port, e.g., a valve for a vacuum pump or a refill bottle that is generally yellow. Also typically included is an inspection glass in which the refrigerant flow or the refrigerant state can be watched.
Further known are installation aids or service devices that do not have manometers, but instead an evaluation unit with a numerical digital display.
The fitter (installer) using these known installation aids does, however, have to be very experienced to be able to perform speedy and reliable maintenance of the air-conditioning system. Accordingly, an improved service device may be beneficial.